Software defined networking (SDN) and its most popular southbound implementation OpenFlow (OF) are already greatly exploited in the existing mobile cellular networks as part of data centers and mobile core networks. Due to user’s mobility, it is of upmost importance for the operators to provide the shortest possible interruption when the mobile users are performing the procedure of handover. In this work, we proposed a novel analytical approach to model the OF-related handover messages exchanged between the OF-switches and the SDN controller. We modeled two different OF-switch implementations and we compared the results: (1) single shared buffer used for the control and data plane; (2) two priority buffers, where the data plane packets are served only when there are no packets to be processed in the control plane. We numerically evaluated the two systems and we validated the model by using simulations. The obtained results clearly point that although the priority buffering increased the complexity, it effectively provided the shortest handover delay. Therefore, the priority buffering should be the preferred mechanism for mobile networks.

作为数据中心和移动核心网络的一部分，现有的移动蜂窝网络已经充分利用了软件定义网络（SDN）及其最流行的南向实现OpenFlow（OF）。由于用户的移动性，当移动用户执行切换过程时，运营商提供尽可能短的中断是最重要的。在这项工作中，我们提出了一种新颖的分析方法来建模在OF交换机和SDN控制器之间交换的与OF相关的切换消息。我们对两种不同的OF开关实现建模，并比较了结果：（1）用于控制和数据平面的单个共享缓冲区；（2）两个优先级缓冲区，其中仅当控制平面中没有要处理的数据包时才服务数据平面数据包。我们对这两个系统进行了数值评估，并通过仿真验证了模型。所获得的结果清楚地表明，尽管优先级缓冲增加了复杂性，但是有效地提供了最短的切换延迟。因此，优先级缓冲应该是移动网络的首选机制。